Recovery of Yttrium Oxide from Titanium-Aluminium based wastes

Abstract

Yttrium belongs to the rare earth elements and critical metals.
Yttrium oxide is mostly used in fluoroscent lamps, production of
electrodes, in electronic filters, lasers, superconductors and as
additives in various titanium-aluminium materials to improve their
properties. Recovery of yttrium oxide from secondary sources
such as red mud, coatings from ceramic industry and phosphors is
extremely important. The main aim of this study is to examine the
selective recovery of yttrium oxide from Al-Ti based secondary
materials using one combined method based mostly on leaching
for selective recovery of yttrium containing: crashing and grinding
of materials, sieving, leaching of chosen fine fraction with
hydrochloric acid, precipitation with oxalic acid in order to produce
a pure yttrium oxalate, filtration and a final thermal decomposition
of yttrium oxalate. The present study summarized mostly the
influence of different reaction parameters such as leaching
temperature, time and concentration of hydrochloric acid on
yttrium dissolution from Al-Ti based secondary materials. An
increase of dissolution time and temperature increases yttrium
dissolution. An increase of pressure from an atmospheric pressure
to 0.5 MPa at 150°C leads to the maximum dissolution of yttrium
(about 98.6 %). The final produced yttrium oxide after thermal
decomposition of yttrium oxalate was analyzed using SEM and
EDS-analysis.